import java.util.Scanner;

/**
 * 1. 求和
 */
public class Main1 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        long sum = 0;
        for(int i = 1;i <= 20230408;i++) {
            sum += i;
        }
        System.out.println(sum);
        scan.close();
    }
}
